大寫和小寫字符串(Uppercase and Lowercase Strings)

您可以通過字符串的uppercaseString和lowercaseString屬性來訪問大寫/小寫版本的字符串。

let normal = "Could you help me, please?"
let shouty = normal.uppercaseString
// shouty 值為 "COULD YOU HELP ME, PLEASE?"
let whispered = normal.lowercaseString
// whispered 值為 "could you help me, please?"